Bjelcic, M. | Search bioRxiv

bioRxiv2025

A user-friendly goniometer-compatible fixed-target platform formacromolecular crystallography at synchrotrons

Fixed-target platforms provide convenient support for microcrystals during serial X-ray crystallography studies using synchrotron radiation. Here, we describe a simple, user-friendly 3D-printed support where the crystals are sandwiched between two layers of thin X-ray transparent membrane resulting in very low scattering background. The platform is compatible with magnetic mounting onto the standard goniometer of macromolecular crystallography beamlines. Our design utilizes a 96-well frame that facilitates hanging-drop experiments directly on the membrane using conventional crystallization plates, thereby eliminating multiple pipetting and crystal handling steps. Crystals can be enclosed into a sandwich and packed into cassettes, preventing the risk of the sample drying out during room-temperature transportation to synchrotron sources. The versatility of the platform is demonstrated by five structures solved using different crystallization- and data-collection strategies. Single crystal rotational-crystallography at both room- and cryogenic-temperatures using large crystals of lysozyme is shown. On-chip microcrystallization is illustrated by use of a photosynthetic reaction center as an example. Finally, serial crystallography data collection at room-temperature from microcrystals of photosynthetic reaction center as well as cytochrome c oxidase crystallized in lipidic cubic phase is presented.

biophysics↗

bioRxiv2023

Exploring serial crystallography for drug discovery

Structure-based drug design is highly dependent on the availability of structures of the protein of interest in complex with lead compounds. Ideally, this information can be used to guide the chemical optimization of a compound into a pharmaceutical drug candidate. A limitation of the main structural method used today, rotational cryo-crystallography, is that it only provides structural information of the protein-complex in its frozen state. Serial crystallography is a relatively new approach that offers the possibility to study protein structures at room-temperature. Here, we explore the use of serial crystallography to determine structures of the pharmaceutical target soluble epoxide hydrolase. We introduce a new method to screen for optimal microcrystallization conditions suitable for use in serial crystallography and present a number of room-temperature ligand-bound structures of our target protein. From a comparison between the room-temperature structural data and previously published cryo-temperature structures, we describe an example of a temperature-dependent difference in ligand-binding mode and observe that flexible loops are better resolved at ambient temperature. Finally, we discuss current limitations and potential future advances of serial crystallography for use within pharmaceutical drug discovery.

biochemistry↗